Green’s Dictionary of Slang

1. (US Und.) a male homosexual.

1935		A.J. Pollock Und. Speaks.
1941		G. Legman ‘Lang. of Homosexuality’ Appendix VII in Henry Sex Variants.
1965		Guild Dict. Homosexual Terms 49: waffle (n.): A male homosexual. (Slang.).
1972		B. Rodgers Queens’ Vernacular 74: stereotype effeminate homosexual [...] waffle (= man with the stamina of a crepe suzette).

2. a woman.

1944		D. Runyon Runyon à la Carte 114: A waffle who is known as Little Oran, though her square monicker is really Magnolia Shapiro.
1945		C.H. Hogan ‘A Yankee ... on Texas Speech’ in AS XX:2 Apr. 82: Incidentally, the woman mentioned above might be a ‘gal’ or a ‘sugah,’ but she would never under any circumstances be a ‘broad,’ [...] or a ‘waffle’ in Texas.